Coupling for coaxial cables



y 7, 1960 A. s. TRUE 2,937,360

COUPLING FOR COAXIAL CABLES Filed Feb. 12, 1958 FIG. I

79 7a &6 9| 85 90 92 96 INVENTOR.

AUGUSTUS S. TRUE BY rd, md,

HIS ATTORNEY.

United States Patent This invention relates to connectorsifor coaxial cables and relates more particular'ly to improved'means "for securing. a firm electricallcontact. with theibraid'ed met'a'l sheath iorming the outer conductor without exerting pressure on or otherwise deformingjthe inner insulation jacket on the axial conductorwhich, would tend to vary the, electrical characteristics of this. cable.

The. invention is illustrated as being embodied in the male. section of a. male and female. detachable connector .for coaxial cables but the inventionl is by no means con- .fiued to thisv particular use.

Certain techniques have been employed .for. making an effective connection with. the outer conductor in the .larger cablesv but these methods have .not beensatiSfactory in miniature .and sub-miniature coaxial cables and the exertion of pressure on the braid. andhcnce on the inner insulation and-conductor by .the. use of a conlst-ricting clamping arrangement produces changes in the electrical characteristics of the cable. Also .the .methods heretofore. used have .not afiorded sufiicient resistance toe pullout iorce, sometimes exerted. on: the cable.

An important object. of the. present invention .is; to :providemeans for. obtaining a'firm clamping contact with thebraided metal of .thecoaxial conductor without transmitting this force radially inwardly of the cable.

Another. "object of, the. invention. is to provide axsimulztaneous clamping action on both the braided sheath. and

the, cable 'jacket to; enable the assembly to- Withstand .a

- pullout forceon the-cable. substantially equal tothe .brealo ing strength of the cable.

A further object of. the invention .is. .to provide .a coaxial connector which can be installed 'on. the endqof theica'ble in a. very minimum amount of timeand. without use of special tools.

Yetxanother object of. the invention .is to provide an assemblywhich can be disassembled and repaired in the field.

Inthe drawing;

:Fig. 1 shows a longitudinal section throughv one section of aconnector. embodying the present invention.

:Fig. 2 is a similar section showing a slightly modified arrangement.

A flexible coaxial cable. is shown. at 10. This cable includes a central or axial conductor 11, an inner insulation jacket 12-, an outer coaxial conductor :or electrical sheath 13 which. may beoif woven or braided copper wire construction, and an external layer of pl-astically deformable insulation 14.

The male connector-comprises a two-part tubular housing including male and female. tubular metal members or sleeves 15- and- 1 6, the former having a longitudinal bore 17 or such diameter as to receive the coaxial cable 10 with a free fit. The sleeve is externally threaded at 20 and has a non-circular wrench-receiving surface 21.

The female sleeve 16 has a bore 22 extending from its inner end and which is internally threaded at 23 to receive threads 20. About midway on the sleeve the bore has an annular shoulder 24 and a bore section 25 of redueed diameter extending to its outer end; The sleeve has a reduced 'outer-diametershown- 26-Which is externally threaded at'27a'nd has-an outer terminal section "30 of about the same diameter 'asse'ctfon- 26;

The contact for' '='theaxial cable 11- which formsno part o'fthe present invention isihust-rat'ed as comprising :a nraleconta'etmember which maybe formed in a single piece and includes, starting "at its-outer "end, a cont-act -portion '31, -a "section 32 of enlarged diameter, a "should'ered portion- '33, and a wire-receiving sleeve 34' at its inner end. For the 'sa'lre of clarity the wire-receiving sleeve portion 34 is shown insection and the remaining portions in elevations. The shouldered portion'has a transverse opening 35 through "which the forward end of the axial conductor, lfl passes and is soldered therein.

Thezinnerinsulation jacket 12 is removed as far as line 36' where the axial 'conductorenters sleeve portion 34.

" An insulating sleeve 41 having an enlarged counterbore section 42 encloses sleeve, 34 and the end of inner insulation jacket 12. When this jacket is removed from the cable back as far as line 36', the braided. conductor is also removed back this. far and the braid of the terniinal .section 43. is. straightened and flared outwardly at right angles. V

A, sleeve 44 .forming one 'of the. principal structural elements of the present invention is now slid over the insulation jacket and back between the braid and said jacket. This sleevehasan'inner diameteras to fit snugly over the insulation and has. an annular flange 45 at 'its outer end which fits within bore .22 of male coupling sleeve 15,.

Another important structural element of the present invention is a sleeve 50 formed of resilient but noncompressible material. and' at each end, of this 'sleeve metal washers '51. and "5.2 are. positionedjin order to prevent rotation imparted. to either of the-relativelyrotatabl'e members.1516., in tighteningv the assembly, to :be "im- 'parted to the sleeve 5.0. and. thus distort it by torsion-a1 forces. Thev outside diameter .ot the sleeve is substantially the same as that. of. bore 22. Various materials can be used for forming- .s'leeve 5.0 and. the essential characteristic of such material is that it bescapabl'e o'f y'ielding under pressure withoutfbringing about a. reduction of its total volume. .Such materialsiinclude silicone. rub- .ber, neoprene and Buna-S.

At the outer curl .of the male connector assembly an insulator 53 is received in snug fit relation in the outer end of bore 25 intubular member .16 which. .has a. bore .54 to receive second section 32 of the male. connector 31 and acounter-bore 55 at its outer end.

In. assembling theparts, the cable is moved .intomale coupling sleeve 15 a distance one or two. inches to the right of the position shown in Fig. 1. Washer-sf 51-52 with, the resilient sleeve 50-therebetweenare now placed on the outer insulation 14.

The metal sleeve 44 is,..-now slipped'into the annular area between the braid whichhasnow been straightened, and the inner insulation jacket. The: cable is now drawn to the left to the position of Fig. 1 and theterminalisection 43-o the braid. is between-washer 52 andilange 45. Insulation 41 is now-fitted .iniplace-and-the. inner'cond'uctorismoved .intoopeningj34 and. soldered. Insuiatbr 53' is. next; assembled on sectionv 32 of the male: contact-:31

' clamping nut '15; returned into' the threaded section-23 of the outer coupling. Continued relative rotation of and the entire assembly -of-;paits is nowxinserted in the coupling sleeve 16 and the threaded inner sleeve gor coupling sleeves 15-16 causes the washers 51-52 to press against opposite ends of resilient sleeve 50 and since the material forming the sleeve cannot be displaced outwardly because of the close fit between bore 22 and the outer periphery of the sleeve, it must travel inwardly against the outer insulation jacket 14, compressing it and l plied equally around its entire periphery. It will be appreciated that the principal purpose of the washers 51-52 is to facilitate relative rotation between the two parts of the tubular housing and that if these washers are omitted the internal shoulders will move against the ends of the plastic sleeve and compress the ends toward each other.

The female section of the connector may be the same as the male connector insofar as the contact means for the braid or outer conductor is concerned. Accordingly only a fragmentary showing of the female connector is made and this includes a female connector member having an outer section 60 to receive male portion 31, a shouldered section 62 similar to section 33 and having a solder opening 63 and an inner sleeve section 64 to receive central conductor 65.

The female connector is received in an insulator 66 and the whole is enclosed in an outer sleeve 70 having a forward section 71. A coupling sleeve 72 having internal threads 73 received on threads 27 of coupling sleeve 16 is flared inwardly at 74 to complete the assembly. If desired, female sleeve 60 may have longitudinal slots (not shown) to cause it to exert a constrictive action on the male contact 31.

Fig. 2 shows only a slight modification in the construction of the connector. Coupling sleeve 78 with its wrench receiving surface 79 is similar to coupling sleeve 15. The coaxial cable including central conductor 80, inner insulation 81, braid 82 and outer insulation 83 is the same as that shown in Fig. 1 and the bore 84 in coupling sleeve is shown as having a larger diameter than the cable. The other coupling sleeve 85 has the same threaded engagement 86 with coupling 78 and has a bore 87 shown as having a larger diameter than resilient sleeve 90 and washers 91-92. The metal sleeve 93 which fits over inner cable insulation 81 has flange 94 and the section 95 of the braid overlying sleeve 93 is shown as being outwardly displaced from the remainder of the braid. The braid terminal 96 is positioned between washer 92 and flange 94. It will be appreciated that as the coupling sleeves 78-85 are rotated relative to each other the material of the resilient ring moves outwardly until it fills the void, after which it moves inwardly, firmly compressing the braid against sleeve 93 and flange 94.

While there have been described herein what are at present considered preferred embodiments of the invention, it will be obvious to those skilled in the art that many modifications and changes may be made therein without departing from the essence of the invention. It is therefore to be understood that the exemplary embodiments are illustrative and not restrictive of the invention, the scope of which is defined in the appended claims, and that all modifications that come within the meaning and range of equivalency of the claims are intended to be included therein.

What I claim is:

1. A connector for the outer conductor of a coaxial cable provided with an inner insulation between inner and outer conductors and an insulating jacket over the latter, said connector comprising a metal tube of substantially uniform diameter throughout its length, positioned between the outer conductor and the inner insulation, a plastically deformable sleeve enclosing the outer insulation in the area of the metal tube and extending at each end thereof to a point which is not beyond the adjoining end of the tube, a two-part tubular enclosure for the deformable sleeve and having a screw threaded engagement therebetween and provided with internal shoulders, and a washer of the same internal and external diameter as the deformable sleeve positioned at each end of said sleeve, whereby relative rotation between the two parts of the tubular enclosure forces the washers against the ends of the plastic sleeve and moves the ends thereof toward each other without any appreciable longitudinal movement of the sleeve relative to the outer insulation, the bore in the enclosure initially being of such size as to receive the sleeve in snug-fit relation and characterized by an absence of voids inside and outside the sleeve so that all of said compressive action moves the plastic mass radially inwardly, firmly compressing the outer insulation against the outer conductor and the latter against the metal tube and effecting firm electrical contact therebetween and exerting sufficient compression of the outer conductor between the outer insulation and the metal tube as to prevent a pull-out of the cable when a force substantially equal to its tensile strength is applied thereto, the metal tube being sufiiciently strong to resist deformation when the compressive force is applied to the plastic sleeve and thus avoid transmitting said compressive force to the central conductor and its insulation.

2. A connector for an outer braided conductor of a coaxial cable provided with an inner insulation between inner and outer conductors and an outer insulation over the latter, said connector comprising a metal tube of substantially uniform diameter throughout its length positioned between the outer conductor and the inner insulation and having a flat annular flange at its forward end contacted by the ends of the braided conductor in the area of the metal tube, a plastically deformable sleeve enclosing the outer insulation in the area of the metal tube and extending at each end thereof to a point which is not beyond the adjoining end of the tube, a two-part tubular enclosure for the plastic sleeve and having a screw threaded engagement therebetween and provided with opposed, internal shoulders, and a washer of the same internal and external diameter as the deformable sleeve positioned at each end of the sleeve, whereby said relative rotation between the two parts of the tubular enclosure forces the washers against the ends of the plastic sleeve and moves the ends thereof toward each other without any appreciable longitudinal movement of the sleeve relative to the outer insulation, the bore in the enclosure initially having a snug-fit relation with the deformable sleeve and characterized by an absence of voids inside and outside the same, so that all of said compressive action moves the plastic mass radially inwardly, firmly compressing the outer insulation against the outer conductor and the latter against the metal tube and effecting firm electrical contact therebetween and between the ends of the braided conductor and said flat annular flange, and exerting a sufficient compression of said braided conductor against the tube and its flange as to prevent a pull-out of the cable when a force substantially equal to its tensile strength is applied thereto.

References Cited in the file of this patent UNITED STATES PATENTS 2,352,159 Brodie June 27, 1944 2,449,570 Violette Sept. 21, 1948 2,673,233 Salisbury Mar. 23, 1954 2,694,187 Nash Nov. 9, 1954 2,785,385 Figueira Mar. 12, 1957 

